An offshore wind farm is a spatially contiguous area in which wind energy installations are established in the sea. They are often situated in the vicinity of shipping routes and can be reached by general shipping traffic. In this case, the ships are exposed to the risk of collision with the offshore wind farms as a result of incorrect navigation. This risk is taken into consideration by equipping individual wind energy installations with position lights, radar reflectors and radio beacons. In order to be able to give warning indications to the ships in the vicinity of the offshore wind farm even when visibility is poor, a foghorn can also be required in the wind farm (see IALA recommendation 0-117 “On the Marking of Offshore Wind Farms”).
In this case, however, offshore wind farms in some instances encompass a great spatial expanse, such that an individual foghorn gives only limited orientation assistance to the traffic participants at sea when visibility is poor, and the regions and directions of movement to be avoided can be poorly determined by the seafarer.